<!DOCTYPE html>
<html lang="en">
	<head>
		<title>three.js webgl - additive animation - skinning</title>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
		<link type="text/css" rel="stylesheet" href="main.css">
		<style>
			a {
				color: blue;
			}
			.control-inactive {
				color: #888;
			}
		</style>
	</head>
	<body>
		<div id="container"></div>
		<div id="info">
			<a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> - Skeletal Additive Animation Blending
			(model from <a href="https://www.mixamo.com/" target="_blank" rel="noopener">mixamo.com</a>)<br/>
		</div>

		<script type="module">

			import * as THREE from '../build/three.module.js';

			import Stats from './jsm/libs/stats.module.js';
			import { GUI } from './jsm/libs/dat.gui.module.js';
			import { OrbitControls } from './jsm/controls/OrbitControls.js';
			import { GLTFLoader } from './jsm/loaders/GLTFLoader.js';

			let scene, renderer, camera, stats;
			let model, skeleton, mixer, clock;

			const crossFadeControls = [];

			let currentBaseAction = 'idle';
			const allActions = [];
			const baseActions = {
				idle: { weight: 1 },
				walk: { weight: 0 },
				run: { weight: 0 }
			};
			const additiveActions = {
				sneak_pose: { weight: 0 },
				sad_pose: { weight: 0 },
				agree: { weight: 0 },
				headShake: { weight: 0 }
			};
			let panelSettings, numAnimations;

			init();

			function init() {

				const container = document.getElementById( 'container' );
				clock = new THREE.Clock();

				scene = new THREE.Scene();
				scene.background = new THREE.Color( 0xa0a0a0 );
				scene.fog = new THREE.Fog( 0xa0a0a0, 10, 50 );

				const hemiLight = new THREE.HemisphereLight( 0xffffff, 0x444444 );
				hemiLight.position.set( 0, 20, 0 );
				scene.add( hemiLight );

				const dirLight = new THREE.DirectionalLight( 0xffffff );
				dirLight.position.set( 3, 10, 10 );
				dirLight.castShadow = true;
				dirLight.shadow.camera.top = 2;
				dirLight.shadow.camera.bottom = - 2;
				dirLight.shadow.camera.left = - 2;
				dirLight.shadow.camera.right = 2;
				dirLight.shadow.camera.near = 0.1;
				dirLight.shadow.camera.far = 40;
				scene.add( dirLight );

				// ground

				const mesh = new THREE.Mesh( new THREE.PlaneGeometry( 100, 100 ), new THREE.MeshPhongMaterial( { color: 0x999999, depthWrite: false } ) );
				mesh.rotation.x = - Math.PI / 2;
				mesh.receiveShadow = true;
				scene.add( mesh );

				const loader = new GLTFLoader();
				loader.load( 'models/gltf/Xbot.glb', function ( gltf ) {

					model = gltf.scene;
					scene.add( model );

					model.traverse( function ( object ) {

						if ( object.isMesh ) object.castShadow = true;

					} );

					skeleton = new THREE.SkeletonHelper( model );
					skeleton.visible = false;
					scene.add( skeleton );

					const animations = gltf.animations;
					mixer = new THREE.AnimationMixer( model );

					numAnimations = animations.length;

					for ( let i = 0; i !== numAnimations; ++ i ) {

						let clip = animations[ i ];
						const name = clip.name;

						if ( baseActions[ name ] ) {

							const action = mixer.clipAction( clip );
							activateAction( action );
							baseActions[ name ].action = action;
							allActions.push( action );

						} else if ( additiveActions[ name ] ) {

							// Make the clip additive and remove the reference frame

							THREE.AnimationUtils.makeClipAdditive( clip );

							if ( clip.name.endsWith( '_pose' ) ) {

								clip = THREE.AnimationUtils.subclip( clip, clip.name, 2, 3, 30 );

							}

							const action = mixer.clipAction( clip );
							activateAction( action );
							additiveActions[ name ].action = action;
							allActions.push( action );

						}

					}

					createPanel();

					animate();

				} );

				renderer = new THREE.WebGLRenderer( { antialias: true } );
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );
				renderer.outputEncoding = THREE.sRGBEncoding;
				renderer.shadowMap.enabled = true;
				container.appendChild( renderer.domElement );

				// camera
				camera = new THREE.PerspectiveCamera( 45, window.innerWidth / window.innerHeight, 1, 100 );
				camera.position.set( - 1, 2, 3 );

				const controls = new OrbitControls( camera, renderer.domElement );
				controls.enablePan = false;
				controls.enableZoom = false;
				controls.target.set( 0, 1, 0 );
				controls.update();

				stats = new Stats();
				container.appendChild( stats.dom );

				window.addEventListener( 'resize', onWindowResize );

			}

			function createPanel() {

				const panel = new GUI( { width: 310 } );

				const folder1 = panel.addFolder( 'Base Actions' );
				const folder2 = panel.addFolder( 'Additive Action Weights' );
				const folder3 = panel.addFolder( 'General Speed' );

				panelSettings = {
					'modify time scale': 1.0
				};

				const baseNames = [ 'None', ...Object.keys( baseActions ) ];

				for ( let i = 0, l = baseNames.length; i !== l; ++ i ) {

					const name = baseNames[ i ];
					const settings = baseActions[ name ];
					panelSettings[ name ] = function () {

						const currentSettings = baseActions[ currentBaseAction ];
						const currentAction = currentSettings ? currentSettings.action : null;
						const action = settings ? settings.action : null;

						prepareCrossFade( currentAction, action, 0.35 );

					};

					crossFadeControls.push( folder1.add( panelSettings, name ) );

				}

				for ( const name of Object.keys( additiveActions ) ) {

					const settings = additiveActions[ name ];

					panelSettings[ name ] = settings.weight;
					folder2.add( panelSettings, name, 0.0, 1.0, 0.01 ).listen().onChange( function ( weight ) {

						setWeight( settings.action, weight );
						settings.weight = weight;

					} );

				}

				folder3.add( panelSettings, 'modify time scale', 0.0, 1.5, 0.01 ).onChange( modifyTimeScale );

				folder1.open();
				folder2.open();
				folder3.open();

				crossFadeControls.forEach( function ( control ) {

					control.classList1 = control.domElement.parentElement.parentElement.classList;
					control.classList2 = control.domElement.previousElementSibling.classList;

					control.setInactive = function () {

						control.classList2.add( 'control-inactive' );

					};

					control.setActive = function () {

						control.classList2.remove( 'control-inactive' );

					};

					const settings = baseActions[ control.property ];

					if ( ! settings || ! settings.weight ) {

						control.setInactive();

					}

				} );

			}

			function activateAction( action ) {

				const clip = action.getClip();
				const settings = baseActions[ clip.name ] || additiveActions[ clip.name ];
				setWeight( action, settings.weight );
				action.play();

			}

			function modifyTimeScale( speed ) {

				mixer.timeScale = speed;

			}

			function prepareCrossFade( startAction, endAction, duration ) {

				// If the current action is 'idle', execute the crossfade immediately;
				// else wait until the current action has finished its current loop

				if ( currentBaseAction === 'idle' || ! startAction || ! endAction ) {

					executeCrossFade( startAction, endAction, duration );

				} else {

					synchronizeCrossFade( startAction, endAction, duration );

				}

				// Update control colors

				if ( endAction ) {

					const clip = endAction.getClip();
					currentBaseAction = clip.name;

				} else {

					currentBaseAction = 'None';

				}

				crossFadeControls.forEach( function ( control ) {

					const name = control.property;

					if ( name === currentBaseAction ) {

						control.setActive();

					} else {

						control.setInactive();

					}

				} );

			}

			function synchronizeCrossFade( startAction, endAction, duration ) {

				mixer.addEventListener( 'loop', onLoopFinished );

				function onLoopFinished( event ) {

					if ( event.action === startAction ) {

						mixer.removeEventListener( 'loop', onLoopFinished );

						executeCrossFade( startAction, endAction, duration );

					}

				}

			}

			function executeCrossFade( startAction, endAction, duration ) {

				// Not only the start action, but also the end action must get a weight of 1 before fading
				// (concerning the start action this is already guaranteed in this place)

				if ( endAction ) {

					setWeight( endAction, 1 );
					endAction.time = 0;

					if ( startAction ) {

						// Crossfade with warping

						startAction.crossFadeTo( endAction, duration, true );

					} else {

						// Fade in

						endAction.fadeIn( duration );

					}

				} else {

					// Fade out

					startAction.fadeOut( duration );

				}

			}

			// This function is needed, since animationAction.crossFadeTo() disables its start action and sets
			// the start action's timeScale to ((start animation's duration) / (end animation's duration))

			function setWeight( action, weight ) {

				action.enabled = true;
				action.setEffectiveTimeScale( 1 );
				action.setEffectiveWeight( weight );

			}

			function onWindowResize() {

				camera.aspect = window.innerWidth / window.innerHeight;
				camera.updateProjectionMatrix();

				renderer.setSize( window.innerWidth, window.innerHeight );

			}

			function animate() {

				// Render loop

				requestAnimationFrame( animate );

				for ( let i = 0; i !== numAnimations; ++ i ) {

					const action = allActions[ i ];
					const clip = action.getClip();
					const settings = baseActions[ clip.name ] || additiveActions[ clip.name ];
					settings.weight = action.getEffectiveWeight();

				}

				// Get the time elapsed since the last frame, used for mixer update

				const mixerUpdateDelta = clock.getDelta();

				// Update the animation mixer, the stats panel, and render this frame

				mixer.update( mixerUpdateDelta );

				stats.update();

				renderer.render( scene, camera );

			}

		</script>

	</body>
</html>
